JP2022114947A - cable - Google Patents

Abstract

To provide a cable capable of preventing degradation of an insulator exposed at a cable terminal due to ultraviolet even when laid under an environment receiving ultraviolet.SOLUTION: A cable 10 comprises: multiple insulated core wires 3 twisted together, and a sheath 5 covering an outer circumference of the multiple insulated core wires 3. Each of the insulated core wires 3 has a conductor 1, and an insulator 2 covering an outer circumference of the conductor 1. An outer circumferential surface of the insulator 2 has a marking with a luminous material applied helically in a longitudinal direction. The insulator 2 comprises an olefin-based resin.SELECTED DRAWING: Figure 2

Description

The present invention relates to cables.

2. Description of the Related Art Cables used for power distribution and the like are twisted together with a plurality of insulated cores each having a conductor coated with an insulator, and are provided with a sheath that covers the outer periphery of the twisted insulated cores. Some of such cables are provided with an identification mark on the outer peripheral surface of the sheath in order to prevent miswiring (see, for example, Patent Document 1). Further, in such a cable, in order to identify a plurality of insulated cores, there are some cables in which identification marks are provided on the insulators of the insulated cores (for example, see Patent Documents 2 and 3).

In the cable described in Patent Literature 1, the outer peripheral surface of the sheath is provided with an uneven shape, and the depressions are printed with a phosphorescent fluorescent paint, thereby preventing the identification display from being lost due to rubbing.
In the cable described in Patent Literature 2, the insulation of the insulated core is formed with strips having releasability to prevent miswiring of conductors during cable construction.
In the cable described in Patent Literature 3, a ring-shaped mark connected in the circumferential direction is printed on the insulator of the insulated wire core so that the mark can be viewed from all directions.

Japanese Patent Application Laid-Open No. 2020-27678 JP 2006-324085 A JP 2014-17124 A

By the way, since polyethylene insulation is weak against ultraviolet rays, when a cable is used in an environment where it is exposed to ultraviolet rays, light shielding treatment such as wrapping a weather-resistant tape on the insulation of the insulated wire core is usually performed. be. However, in an environment where it is determined that the ultraviolet rays do not hit, there are cases where the light shielding treatment is not performed. In this case, when performing construction and inspection at night in an installation environment such as an outdoor switchboard, there is a high possibility that the worker will miss the entry of ultraviolet rays into the switchboard through the gaps in the door and drain holes. In particular, it is difficult for the operator to notice that the terminal portion of the cable connected to the power meter in the switchboard is exposed to ultraviolet rays because it is difficult to see from the outside.

If the UV rays were overlooked during construction and the tape was not wrapped, and the UV rays were not noticed during inspection, the sheath would be peeled off and exposed at the cable end due to prolonged exposure to UV rays. deterioration progresses. Even when the cables of Patent Documents 1 to 3 are laid, the operator cannot notice, during inspection, that the exposed insulator at the cable end is exposed to ultraviolet rays.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and its object is to prevent deterioration of the insulator exposed at the cable end due to ultraviolet rays even when installed in an environment exposed to ultraviolet rays. is to provide

In order to achieve the above objects, the cable according to the present invention is characterized by the following (1) to (3).
(1) a plurality of insulated wire cores twisted together;
A cable comprising a sheath covering the outer periphery of the plurality of insulated wire cores,
The insulated wire core is
a conductor;
and an olefin-based insulator covering the outer periphery of the conductor,
Marking made of a luminous material is applied to the outer peripheral surface of the insulator in a longitudinal spiral shape,
cable.
(2) an uneven portion is provided on the outer peripheral surface of the insulator;
The marking is applied to the uneven part,
The cable according to (1) above.
(3) the conductor has a cross-sectional area of 2 square millimeters or less;
The cable according to (1) or (2) above.

According to the cable having the configuration of (1) above, the marking emits light during inspection work at night, even if the cable is installed without being subjected to light shielding treatment because it is overlooked that it is in an environment exposed to ultraviolet rays. Thus, the worker can be made aware of the entry of ultraviolet rays. Therefore, the operator can prevent deterioration of the insulator by applying light shielding treatment such as tape wrapping to the cable.

According to the cable having the configuration (2) above, since the phosphorescent material enters the recess, the print strength against rubbing is improved.

According to the cable having the configuration (3) above, deterioration of the insulator due to ultraviolet rays can be effectively prevented when thin-sized insulated cores are used.

According to the cable of the present invention, even when the cable is installed in an environment exposed to ultraviolet rays, deterioration of the exposed insulator at the cable end due to ultraviolet rays can be prevented.

The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading the following detailed description of the invention (hereinafter referred to as "embodiment") with reference to the accompanying drawings. .

FIG. 1 is a perspective view of an insulated wire core according to one embodiment of the present invention. FIG. 2 is a perspective view of a cable according to one embodiment of the invention.

Specific embodiments relating to the present invention will be described below with reference to each drawing.

FIG. 1 is a perspective view of an insulated wire core 3 according to one embodiment of the present invention, and FIG. 2 is a perspective view of a cable 10 including the insulated wire core 3 of FIG. The cable 10 is, for example, a power cable, and is laid in a switchboard or the like.

An insulated wire core 3 shown in FIG. The insulator 2 is an olefin-based insulator containing an olefin-based resin such as polyethylene, and deteriorates when exposed to ultraviolet rays.

On the outer peripheral surface of the insulator 2, markings M1 and M2 (sometimes referred to as "markings M") made of phosphorescent paint are applied in a spiral shape in the longitudinal direction of the insulating wire core 3. The phosphorescent paint has the property of storing a part of the energy of the received light (ultraviolet region) and emitting it as visible light. Since the phosphorescent paint emits light when exposed to ultraviolet rays (UV) such as sunlight, the markings M1 and M2 emit light in a dark environment such as at night and become easily visible.

The markings M1 and M2 are printed on the outer peripheral surface of the insulator 2 at symmetrical positions with respect to the axial center of the insulating wire core, and have contents such as "UV caution" printed in a spiral shape in the longitudinal direction. The markings M1 and M2 are provided on the outer peripheral surface of the insulator 2 at intervals of spiral pitches SP1 and SP2, respectively.

By applying the markings M1 and M2 in this manner, the markings M1 and M2 can be easily seen when the insulated wire core 3 is viewed from any direction, and the entire outer peripheral surface (front surface) of the insulated wire core 3 Compared to printing, the amount of phosphorescent paint used can be reduced.

In addition, the insulator 2 is formed by adjusting the cooling conditions when the resin material is extruded around the conductor 1 so that the surface (outer peripheral surface) of the insulator 2 is moderately roughened to form fine irregularities. The markings M1, M2 are applied to this indentation. In this way, the phosphorescent paint enters the recesses, thereby improving the print strength against rubbing.

As shown in FIG. 2 , the cable 10 includes a plurality of (three in FIG. 2 ) insulated wire cores 3 that are twisted together, and a sheath 5 that covers the outer periphery of the plurality of insulated wire cores 3 . The sheath 5 is made of resin such as polyvinyl chloride. In the cable 10, a plurality of insulated wire cores 3 are provided with helical markings M. As shown in FIG.

An example of a method for manufacturing the cable 10 will be described.
First, the insulator 2 is extruded on the conductor 1 . At this time, the cooling conditions are adjusted so that fine irregularities are formed on the surface of the insulator 2 . Next, on the outer peripheral surface of the insulator 2, characters of "Caution against UV" are continuously printed linearly in the longitudinal direction of the conductor 1 to prepare an insulated wire core with print. In printing, the luminous paint enters the recesses formed on the surface of the insulator 2, thereby improving the printing strength against rubbing.
Subsequently, in an electric wire twister, each of the plurality of printed insulated cores is primarily twisted to prepare an insulated core 3, and the plurality of insulated cores 3 are twisted together (secondarily twisted) to form a wire. Create a core strand. The primary twist pitch becomes the marking spiral pitch (SP1, SP2). Thereafter, the cable 10 is produced by extruding the sheath 5 around the core strand.

As described above, before the insulated wire core 3 is twisted, the letters "Caution against UV" are continuously printed linearly in the longitudinal direction on the outer peripheral surface of the insulator 2 . When the plurality of insulated wire cores 3 are twisted together, the insulated wire cores 3 are twisted at a predetermined pitch, so that spiral markings M1 and M2 are applied to the outer peripheral surface of the insulated wire cores 3 . Therefore, the spiral pitches SP1 and SP2 of the markings M1 and M2 match the predetermined pitch of the insulated wire core 3 . That is, if the character string "Caution for UV" is printed linearly on the outer peripheral surface of the insulator 2, then the spiral markings M1 and M2 are applied to the insulator 2 by going through the same process as a normal cable manufacturing method. 2 can be formed on the outer peripheral surface. Therefore, the cable 10 having a shape in which the insulated wire cores 3 with the markings M are twisted can be realized by using a normal printing machine for linearly printing characters without using a special printing machine.

Olefin insulation is vulnerable to ultraviolet rays, so when a cable is used in an environment where it is exposed to ultraviolet rays, light shielding treatment such as wrapping a weather-resistant tape on the insulation of the insulated wire core is usually applied in advance. . However, in an environment where it is determined that the ultraviolet rays do not hit, there are cases where the light shielding treatment is not performed. In this case, in an installation environment such as an outdoor switchboard, there is a high possibility of overlooking the entry of ultraviolet rays into the switchboard through a gap in the door or a drain hole during construction and inspection at night. In particular, it is difficult for the operator to notice that the terminal portion of the cable connected to the power meter in the switchboard is exposed to ultraviolet rays because it is difficult to see from the outside.

For this reason, with a general cable, if the penetration of ultraviolet rays is overlooked during installation and the tape is not wrapped, and if the penetration of ultraviolet rays is not noticed during inspection, the ultraviolet rays will continue to hit the cable for a long period of time. As a result, deterioration of the insulator exposed by stripping the sheath at the cable end progresses.

According to the cable 10 of the present embodiment, the marking M emits light during inspection work at night, even if the cable 10 is installed without being subjected to light shielding treatment because it is overlooked that it is in an environment exposed to ultraviolet rays. Thus, the worker can be made aware of the entry of ultraviolet rays. Therefore, the operator can prevent deterioration of the insulator 2 by applying light shielding treatment such as tape wrapping to the cable 10 .

In addition, in the case of a thick insulated wire core 3 having a conductor cross-sectional area of 3.5 mm ² or more, the twist pitch of the insulated wire core 3 corresponding to the spiral pitches SP1 and SP2 is widened and installed in a narrow switchboard. Visibility may be reduced in some cases. In addition, deterioration of the insulator 2 tends to progress more easily when the thickness of the insulator 2 is thinner. Therefore, in the cable 10 of the present embodiment, when the conductor cross-sectional area of the insulated wire core 3 is 2 mm ² or less, the marking M emits light during inspection work at night, so that the operator can be made aware of the entry of ultraviolet rays. The effect of being able to do it can be further exhibited.

In the above-described embodiment, the marking M is applied to the insulating wire core 3 by printing the phosphorescent paint on the outer peripheral surface of the insulator 2, but the method of applying the marking M is not limited to this. For example, the marking M may be applied using a phosphorescent material, such as by extruding a phosphorescent resin onto the insulator 2 to apply the marking M.

Here, the features of the cables according to the above-described embodiments of the present invention are summarized and listed briefly in [1] to [4] below.
[1] A plurality of insulated wire cores (3) twisted together;
A cable (10) comprising a sheath (5) covering the outer periphery of the plurality of insulated wire cores,
The insulated wire core (3) is
a conductor (1);
and an olefin insulator (2) covering the outer periphery of the conductor,
A marking (M) made of a luminous material is spirally applied to the outer peripheral surface of the insulator in the longitudinal direction of the insulating wire core,
Cable (10).
[2] An uneven portion is provided on the outer peripheral surface of the insulator,
The marking is applied to the uneven part,
The cable according to [1] above.
[3] the conductor has a cross-sectional area of 2 square millimeters or less;
The cable according to [1] or [2] above.
[4] A method for manufacturing the cable (10) according to any one of [1] to [3] above,
extruding said insulator (2) on said conductor (1);
creating an insulated wire core with a marking by linearly marking the outer peripheral surface of the insulator (2) in the longitudinal direction of the conductor (1);
Each of the plurality of insulated wire cores with markings is primarily twisted to prepare an insulated wire core (3) to which the marking is applied in a spiral shape, and the plurality of insulated wire cores are twisted together to twist the core. create a body
extruding a sheath (5) around the core strand;
A method for manufacturing a cable (10).

REFERENCE SIGNS LIST 1 conductor 2 insulator 3 insulated wire core 5 sheath M, M1, M2 marking SP1, SP2 spiral pitch

Claims (3)

a plurality of insulated wire cores twisted together;
A cable comprising a sheath covering the outer periphery of the plurality of insulated wire cores,
The insulated wire core is
a conductor;
and an olefin-based insulator covering the outer periphery of the conductor,
Marking made of a luminous material is applied to the outer peripheral surface of the insulator in a longitudinal spiral shape,
cable. An uneven portion is provided on the outer peripheral surface of the insulator,
The marking is applied to the uneven part,
Cable according to claim 1. the cross-sectional area of the conductor is no greater than 2 square millimeters;
Cable according to claim 1 or 2.

Images